Distribution of CB1 cannabinoid receptors in the rat amygdaloid complex

The amygdaloid complex (AK) has a very important role in the
modulation of endocrine and visceral functions, in complex behavioral
mechanisms such as defence, feeding, aggression, affects,
reproduction, memory and learning. The aim of this study was to
determine the precise distribution of cannabinoid CB1 receptors in the
rat AK, using the immunohistochemical (ABC) method.
According to our results, CB1-immunoreactivity in the rat AK was
highest in the medial nucleus. Slightly lower immunoreactivity was
found in the basolateral nucleus. Moderate density of CB1 receptors
occurred in the central, basomedial, lateral and posterior nuclei of the
AK. CB1-immunoreactivity in all of these nuclei was present in the form
of discrete spot-like precipitates of unequal size and appearance.
These precipitates exhibited three different patterns: 1. elongated
columns or lines, 2. complete or incomplete rings and 3. in a small
number of AK regions CB1-immunoreactivity was separately dispersed
in the form of single spot-like precipitates between more complex
columns and rings of precipitates.
Considering the functional importance of amygdala and the
distribution of CB1 receptors in the AK we could conclude that our
findings suggest a role for cannabinoids in modulating responses of
the AK to stress and fear as well as to pain.